Stockholders' Equity (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended				12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Stock Repurchase Program
Shares Repurchased Under Board Authorization					1,336,132	1,992,831	2,671,637
Total cost (in dollars)					$ 22.1	$ 42.0	$ 48.2
Average share price (in dollars per share)					$ 16.55	$ 21.10	$ 18.03
Shares repurchased to satisfy minimum statutory withholding tax upon the net settlement of equity awards					391,195	418,135	367,367
Dividend Program
Dividend declared (in dollars per share)	$ 0.07	$ 0.07	$ 0.07	$ 0.07
Dividend paid (in dollars per share)	$ 0.07	$ 0.07	$ 0.07	$ 0.07
Aggregate cash dividends					$ 9.1
Aggregate stock dividends					$ 0.3
May 2013
Stock Repurchase Program
Amount Authorized by Board (in shares)	4,000,000				4,000,000
Total Shares Purchased					4,000,000
Shares Repurchased Under Board Authorization						800,000	2,700,000
October 2014
Stock Repurchase Program
Amount Authorized by Board (in shares)	4,000,000				4,000,000
Total Shares Purchased					2,500,000
Shares Remaining Under Board Authorization	1,500,000				1,500,000
Shares Repurchased Under Board Authorization					1,300,000	1,200,000